Hey young un's,
That's B.S. When i finished the 3U last year, I was 100% certain i would get 100%. Like I finished in 47 mins, and had well over an hour to check. You know those solns that some guy put up for 3U/4U, he did that last year too. I checked it, and I thought, 100 FOR SURE. BUT, I still only freaking got 99. So you don't always know whether you are right...
Secondly, all you peeps saying 04 was harder than other papers, you will find that ppl say that every year. Like when we finished 03 everyone thought it was the hardest yet. What I reckon is, all the practice papers you do just isnt done in the "HSC environment". The pressure adds a lot to the difficulty. From looking at the 04 paper, I think it was at the same level as 03 (maybe a little longer). So if you knew your stuff, you should have been fine (your 7 (b) looks a little easier than our 7 (b)).
Oh, I REALLY think your paper favoured 4U kids toooo much. I STILL REMEMBER doing a q very similar to your 7 (a) in a 4U class.
I think 3U scales pretty well. From talking to my friends, I think if you got around 70/84 you should get band 6. You need to get 83 or 84 to get 100. Trust me, its easier than u think to make dumb little mistakes. I think what separates ppl who get 97+ is dumb mistakes.
Good Luck !
P.S. It's very easy to forget maths. So if you want to tutor or something, keep refreshing yourself... unless you're gonna do maths at uni (which u would have to if u do BSci or BEng or something).